The treatment of cellulose-containing fabrics with liquid ammonia has been known for a long period of time. For example, mercerization of cellulosic textile materials with liquid ammonia forms the subject matter of British Pat. No. 374,791 having a priority date (Germany) of Apr. 1, 1931. Since that time, a variety of patents and publications, many of which are identified herein below, have described various processes and techniques for the treatment of fabrics, yarn, and threads with liquid ammonia for various purposes.
Notwithstanding the substantial development effort which has taken place over the years, liquid ammonia processing has not had any significant commercial success in connection with the mercerizing or other finishing treatment of fabrics. Primarily, this has been due to the enormous amount of shrinkage which is induced in the fabric by reaction with the liquid ammonia processing fluid. Notwithstanding the other desirable effects achieved by the liquid ammonia reaction, the "loss" of yardage in the treating process has been so great as to substantially preclude the practical use of liquid ammonia processing in commercial finishing lines.
Significant advancement in techniques of liquid ammonia processing is reflected in the Lindberg et al. U.S. Pat. No. 3,406,006, for example, in which working relationships are sought to be established between application of controlled tension to the fabric, in relation to the amount of processing time, as a means of avoiding excessive shrinkage. However, this approach has important limitations in the context of a commercial finishing line, in which fabric is being processed continuously in web form. The application of tension in the width or filling direction, to a continuously moving web of fabric, is fraught with difficulty and complications. Thus, the invention of the Lindberg et al. patent, while constituting an interesting and significant advance, has not resulted in widespread commercial utilization of liquid ammonia processing techniques, because of the attendant problems in controlling shrinkage loss.
Other patents and publications of interest, dealing with liquid ammonia processing of fabrics, are as follows: Mahn U.S. Pat. No. 1,998,551, Estes U.S. Pat. No. 3,347,963, Webb U.S. Pat. No. 3,511,591, Gailey U.S. Pat No. 3,560,140, Troope et al. U.S. Pat. No. 3,589,030, Skaathun et al. U.S. Pat. No. 3,664,158, Calamari, Jr. et al. U.S. Pat. No. 3,724,243, Calamari, Jr. et al. U.S. Pat. No. 3,767,359, Calamari, Jr. et al. U.S. Pat. No. 3,849,067. Gogek Canadian Pat. No. 810,572. Great Britain Pat. No. 841,401. "Effect of Preswelling on Durable-Press Performance of Cotton", Textile Research Journal, June 1969, pp. 543-7.